Portion of a keyboard



FIG. 1 is a top front perspective view of a portion of a keyboardshowing my new design;

FIG. 2 is a top view thereof;

FIG. 3 is a left side view thereof; and,

FIG. 4 is a front view thereof.

The broken line showing of the remainder of the keyboard forms no partof the claimed design.

The ornamental design for a portion of a keyboard, as shown anddescribed.